Question

Simplify the following expression.
\[\sqrt{-18}\sqrt{-72}\]

Answer 1

\[\sqrt{(-18)(-72)}\]

can you use a calculator?

Answer 2

maybe

Answer 3

I DONT HAVE ONE

Answer 4

HELP PLEASE

Answer 5

I think the question was more - are you allowed to on this problem.

Answer 6

okay..i'll do this the manual way...

Answer 7

yuppp that's what i meant thanks @chris :D

Answer 8

np =). and I think we're assuming not allowed heh.

Answer 9

\[\sqrt{-18}\sqrt{-72}\neq \sqrt{(-18)(-72)}\]

Answer 10

oh man..made a mistake in one :O

Answer 11

WHAT WAS THE MISTAKE

Answer 12

isn;t it @Zarkon ? isn't \[\sqrt{a}\sqrt{b} = \sqrt{(a)(b)}\]?

Answer 13

if \(a,b\ge 0\)

Answer 14

oh..hmm..yeah..this is imaginary now that i think about it..

Answer 15

\[\sqrt{-18}\sqrt{-72}\]

\[=i\sqrt{18}\times i\sqrt{72}\]
\[=i^2\sqrt{18}\times \sqrt{72}\]
\[=-\sqrt{18\times 72}\]
\[=-\sqrt{18\times 2\times 36}\]
\[=-\sqrt{36\times 36}=-36\]

Answer 16

hmm yeah..went pretty careless there..sorry :)

Answer 17

im confused

Answer 18

THANKS EVERYONE

Answer 19

\[\sqrt{-a} = i \sqrt{a}\]

he just factored an i..then when i^2..it became -1...my other mistake was the 2 i pulled out..i wrote 4 so my answered doubled..do you get it now?

Answer 20

YES